Guidance system mounts for surgical introducers

ABSTRACT

A delicate tissue retraction system having a retractor, an introducer and a clamp mechanism. The retractor has a hollow retractor passage and the introducer has an introducer channel extending from a proximal introducer end to a distal introducer end. The introducer is configured to be removably installed within the retractor. The clamp mechanism is on the introducer and includes a probe shaft receptacle suspended inwardly from the introducer wall to form one or more open spaces between the introducer wall and the probe shaft receptacle. The probe shaft receptacle has a clamp passage that is axially aligned with the introducer channel and dimensioned to receive the shaft of a navigation probe therethrough. The probe shaft receptacle has a clamp configured to selectively reduce a size of at least a first portion of the clamp passage to selectively hold the probe shaft at a fixed position relative to the introducer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of and priority to U.S. ProvisionalApplication No. 61/992,378, filed on May 13, 2014, and U.S. applicationSer. No. 14/711,305, filed on May 13, 2015, both of which areincorporated herein by reference in the entirety.

FIELD OF THE INVENTION

The present invention relates to surgical retractor systems andapparatus for securely connecting guidance system components to suchretractor systems. The present invention also relates to apparatus forindicating when a guidance system component is in proper registrationwith a surgical introducer.

Background

A variety of different devices have been used to retract delicate tissueduring surgical procedures. One such device is illustrated in UnitedStates Patent Publication Number 2010/0010315 (“Mangiardi I”), which isincorporated herein by reference in its entirety. Mangiardi I shows twogeneral versions of a retractor for delicate tissue. One version is aclosed-channel retractor in the form of a tube (see, e.g., Mangiardi IFIG. 3), and the other is an open-channel retractor in the form of acurved channel (see, e.g., Mangiardi I FIG. 23).

FIG. 1 of this application illustrates a soft tissue retractor systemsuch as found in Mangiardi I. The retractor system includes a hollowretractor 100, and an introducer 102 that is selectively inserted intothe retractor 100. The retractor 100 and/or introducer 102 may include ahandle 104 to facilitate manipulation and placement of the retractorsystem, and a lock to hold the introducer and retractor together. Theillustrated handle 104 is molded integrally with the retractor 100, butit may be a separate part. The handle 104 may be configured to connectto a clamp 106, such as the standard surgical clamp 106 shown in FIG. 1.In this example, the handle 104 has a ridge 108 that fits into acorresponding groove 110 on the clamp 106, to prevent relative rotationbetween the two when engaged. Modifications to this design are describedin Mangiardi I.

A retractor system such as shown in FIG. 1 is often used by insertingthe introducer 102 into the retractor 100 and locking it in place, sothe two can be moved and manipulated as a unit. The combined retractorsystem is inserted into the patient's body and moved to the surgerysite, and then the introducer 102 is unlocked and removed to permitaccess to the site through the retractor 100. When the unit is in place(either before or after the introducer 102 is removed), the handle 104may be locked to a clamp 106 to hold the retractor 100 in place. Anexample of this procedure is shown in FIGS. 16-20 of Mangiardi I.Surgeons using the Mangiardi I retractor sometimes do not use a clamp tohold the retractor at the surgery site, and often manually manipulatethe retractor to access different parts of the surgery site during thesurgical procedure. The retractor system and the retractor may bemanipulated by holding the proximal ends of the introducer or retractoror by holding the handle.

The device shown in Mangiardi I may have a transparent introducer 102and/or retractor 100, and surgeons using such devices advantageously usethe transparent introducer and retractor to manually guide the unit tothe surgery site. While it has been found that visual guidance bylooking through the introducer 102 is very beneficial, it also has beenfound that some form of additional guidance or navigation may be desiredin some cases. For example, in some cases, surgeons have used a probe orguide wire (a narrow elongated rod) to guide the movement of theretractor system. In such cases, the probe is advanced to the surgerysite, and then the interlocked retractor system is slid over the probeuntil it reaches the surgery site. This is facilitated by the inclusionof a hole at the tip of the introducer that fits around the probe. Ifthe hole through the tip of the introducer is absent, this method cannotbe used. This type of system is described in United States PatentPublication Numbers 2008/0109026 and 2009/0048622, which areincorporated herein by reference. These references also show analternative construction, in which the retractor is not locked to theintroducer.

It has been found that some surgeons using the above procedure may use aprobe that is integrated into a computer navigation system. For example,the probe may include a so-called “starburst” or the like, on theprobe's proximal end (i.e., the end opposite the distal end that isinserted to the surgical site). This and other navigation systems areknown in the art. For example, frameless navigation systems and othercomputerized guidance systems and methods are described in U.S.Publication No. 2001/0027271 (which is incorporated herein by referencein its entirety) and others, and are commercially available fromcompanies such as Medtronic, Inc., Stryker, BrainLab, AG, and GEHealthcare. As used herein, “computerized guidance” encompasses anymethod of guiding a device to or at a surgical site that relies oncomputer visualization and/or control. Mangiardi I briefly notes thepossibility of using stereotactic guidance or navigation in conjunctionwith a surgical retractor, but does not illustrate or describe thisprocedure or any apparatus for accomplishing this objective.

While computerized surgical guidance systems are well-known, a number oflimitations exist with respect to their use with retractor systems, andparticularly with systems like those shown in Mangiardi I. For example,while some surgeons use computerized guidance to direct a probe to thesurgery site, and then slide the retractor system over the probe to thesite, the movement of the retractor may be somewhat imprecise and theprocess can be unduly cumbersome. This method also is not available ifthe retractor system does not have a through-hole that fits over theprobe (due either to the absence of a hole or a hole that is too small).In addition, the probe does not provide a view of the tissue throughwhich it is advanced, so there is no visual means to perceive and avoidcritical tissue (e.g., major blood vessels or nerves) when inserting aprobe before inserting a retractor/introducer system. Also, thesmall-diameter probe may sever delicate tissue cells, such as grey orwhite brain matter, rather than moving the cells aside and passingbetween them as would be expected to happen when advancing the retractorsystem.

United States Patent Publication Number 2013/0066154 (“Mangiardi II”),shows examples of systems for integrating a navigation probe into asurgical introducer. For example, FIGS. 1-6 of Mangiardi II shows anavigation probe that is secured to the inside of a pre-existingintroducer by resilient means, such as rubber plugs or O-rings. Anotherversion of the Mangiardi II device uses a slip fit (e.g., FIGS. 7-8),and still another version uses an arm to hold the probe down inside theintroducer (FIG. 9). Still other versions mount the navigation deviceoutside the introducer, to an arm that is connected to the retractorassembly (FIGS. 10-11). While these systems may provide suitableperformance, they also have certain potential shortcomings. For example,resilient plugs may slip in the presence of fluids, a slip fit requirescareful monitoring to ensure proper positioning, an arm as shown in FIG.9 to hold the probe in place requires the probe to be modified toinclude a surface against which the arm pushes, and locating thenavigation device outside the introducer complicates the correlationbetween the navigation device and the tip of the introducer orretractor.

United States Patent Publication Number 2012/0071748 shows anotherexample of a system for integrating a navigation probe into a surgicalintroducer. In this case, the probe is retained in a narrow channelthrough the introducer, and held in place with a threaded locking screw.The locking screw adds an additional potentially-removable part to theoperating theater, and therefore this reference adds a separateretaining device (see FIG. 7B) to prevent the locking screw from beingremoved.

It has been found that there still remains a need to provide alternativeapparatus and methods for coordinating the use of guidance systems withsurgical introducers.

SUMMARY OF THE INVENTION

In one aspect, there is provided a delicate tissue retraction system foruse with a navigation probe having a probe shaft and a probe tip at adistal end of the probe shaft. The delicate tissue retraction systemincludes a retractor, an introducer, and a clamp mechanism. Theretractor has a hollow tubular retractor passage extending along alongitudinal axis from a proximal retractor end to a distal retractorend. The introducer has an introducer wall forming an introducer channelextending from a proximal introducer end to a distal introducer end. Theintroducer is configured to be removably installed within the retractorsuch that the proximal introducer end and distal introducer end arelocated along the longitudinal axis and the distal introducer endextends beyond the distal retractor end. The clamp mechanism is locatedat the proximal introducer end, and includes a probe shaft receptacleand a clamp. The probe shaft receptacle is suspended inwardly from theintroducer wall to form one or more open spaces between the introducerwall and the probe shaft receptacle, and has a clamp passage that isaxially aligned with the introducer channel and dimensioned to receivethe probe shaft therethrough. The clamp is configured to selectivelyreduce a size of at least a first portion of the clamp passage toselectively hold the probe shaft at a fixed position relative to theintroducer.

In some aspects, the probe shaft receptacle has a slot intersecting theclamp passage at the first portion of the clamp passage. The clamp maybe configured to compress the probe shaft receptacle at the slot tothereby hold the probe shaft at the fixed position relative to theintroducer. An outer surface of the probe shaft receptacle at the slotmay include a tapered wall, and the clamp may have a collar thatsurrounds the tapered wall and is movable between a first position inwhich the probe shaft is movable relative to the probe shaft receptacleand a second position in which the probe shaft is held at the fixedposition relative to the probe shaft receptacle.

In some aspects, the clamp mechanism spans the introducer channel from afirst point at the introducer wall to a second point at the introducerwall.

In some aspects, at least a portion of the introducer wall is atransparent material, and the one or more open spaces are dimensioned toallow visualization past the probe shaft receptacle, along theintroducer channel, and through the transparent material.

In some aspects, the introducer includes a mount extending into theintroducer channel at the distal introducer end and positioned tosurround the probe tip when the navigation probe is at a fully insertedposition within the introducer. In some cases, the mount may be a ringor a plurality of ribs.

In some aspects, the first portion of the clamp passage includes a fixedanvil and a movable clamp part, and the clamp further includes a controlmember that is rotatable between an open position in which the movableclamp part is relatively far from the fixed anvil, and a closed positionin which the movable clamp part is relatively close to the fixed anvilto hold the probe shaft at the fixed position relative to theintroducer. The movable clamp part may be a tension band. The controlmember may be a cam that is rotatable between an unlocked position inwhich the movable clamp part is in the open position, and a lockedposition in which the movable clamp part is in the closed position. Thecontrol member may be a lever that is pivotally mounted to the remainderof the clamp mechanism to rotate through an angle of about 90° betweenthe open position and the closed position.

In some aspects, the clamp passage is located at a central geometricaxis of the introducer. The distal introducer end may terminate at anintroducer tip located along the central geometric axis of theintroducer.

In some aspects, the system may include a registration indicatorconfigured to indicate when the navigation probe is at a properregistration position with respect to the introducer. The registrationindicator may be movably mounted to the clamp mechanism to slide alongthe longitudinal axis between a first indicator position in which theregistration indicator indicates that the probe is not at the properregistration position, and a second indicator position in which theregistration indicator indicates that the probe is at the properregistration position. The registration indicator may have a proximalindicator end, a distal indicator end, and a shaft joining the proximalindicator end and the distal indicator end. The shaft may be a hollowtube. The distal end may have a probe tip receptacle having an openingthrough which the position of the probe tip can be viewed. Theregistration indicator may include a resilient member configured to biasthe registration member to move towards the first indicator position.

In some aspects, the clamp mechanism is removably connected to theintroducer. The clamp mechanism may be secured to the introducer byscrews.

The foregoing summary of the invention provides a variety of exemplaryembodiments that may be used in any suitable combination, and is notintended to impose any limitations upon the invention recited in theclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

A better understanding of the exemplary embodiments may be understood byreference to the attached drawings, in which like reference numbersdesignate like parts. The drawings are exemplary, and not intended tolimit the claims in any way.

FIG. 1 is an example of a prior art delicate tissue retractor system.

FIGS. 2 and 3 show an embodiment of an introducer, clamp, and navigationprobe, with the clamp in the clamped and unclamped positions,respectively.

FIG. 4 shows an example of a tension band that may be used withembodiments of the invention.

FIGS. 5A and 5B show another example of a clamp in the unclamped andclamped positions, respectively.

FIG. 6 is a cross-sectional view showing an exemplary introducer, clamp,navigation probe, and registration indicator.

FIGS. 7A and 7B show the registration indicator of FIG. 6 in twopositions.

FIG. 8 is an exploded view of another exemplary retractor system, shownwith a registration indicator and a navigation probe.

FIG. 9A is a cutaway side view of the embodiment of FIG. 8, shown withthe probe partially installed and the clamp in the unclamped position.

FIG. 9B is a cutaway side view of the embodiment of FIG. 8, shown withthe probe fully installed and the clamp in the clamped position.

FIG. 10 is another embodiment of an introducer, clamp and navigationprobe system.

BRIEF DESCRIPTION OF EMBODIMENTS

Embodiments of the invention may provide various features to supplementor advance the state of the art of surgical introducers and retractorsystems. For example, embodiments may extend the capability ofconventional surgical retractors by proving a system to securely hold aguidance system probe or by providing an indicator to identify when theprobe is not properly positioned. As used herein, the term “guidance” isintended to include any system for assisting a surgeon with advancingthe retractor system to the surgery site, and can include passivesystems like guide wires, or active systems like navigation probes thatare detected and tracked using a computerized telemetry system. (Theterm “surgeon” includes anyone in the operation theater who might use ormanipulate the introducer system.) Active probes can be trackedoptically by a “starburst” or other marker mounted on a portion of theprobe that remains visible during the procedure, by directly monitoringthe tip of the probe using radiation imaging (e.g., X-ray) or magneticimaging, by physically connecting the probe to a frame of referencesystem to mechanically track the position of the probe, or by othermeans or combination or means, as known in the art. The terms“navigation” and “guidance” are used interchangeably herein. Embodimentsalso may be used with manual systems in which the surgeon moves theretractor system entirely by hand, or semi-automated or automatedsystems that operate under the surgeon's control or automaticallyadvance the retractor system to the surgery site without the surgeon'sintervention.

Embodiments may be used with dedicated systems that are designed anew,or with preexisting systems. For example, embodiments may be used withsystems like the one shown in FIG. 1, such as by supplementing,modifying or replacing the introducer 102, or with other introducerassemblies, as will be appreciated by persons or ordinary skill in theart. The following embodiments described herein may be used with aretractor 100 as shown in FIG. 1, or in other retractors. It will bereadily appreciated that the shape of the introducer can be modified tofit into any conventional retractor, and the introducer also may bemodified to connect to the retractor (if necessary or desired) using anysuitable clamp or other engagement mechanism. For example, embodimentsmay be used with small-scale versions of introducers like the one shownin FIG. 1, in which the embodiment optionally may be scaled down toallow visibility into the retractor, but providing such visibility isnot required in all embodiments.

The exemplary embodiments described herein are directed towardsintroducers for use in neurosurgery or other operations in and aroundthe brain or skull. However, uses in other parts of the body are alsopossible.

FIG. 2 shows an exemplary embodiment of an introducer 200 that isconfigured to releasably connect with a navigation probe 210. Theintroducer 200 is configured to fit into a conventional retractor, suchas those shown in FIG. 1 or those otherwise available from Vycor Medicalof Boca Raton, Florida, but other retractors—such as custom-builtretractors—may be used.

The introducer 200 is constructed as a hollow channel 202 that extendsalong a longitudinal axis 204. The channel 202 may be closed (i.e.,without perforations or openings, but alternatively may include openingsthrough the sidewall of the channel 202. The channel 202 may have acurved cross-section as viewed along the longitudinal axis 204. Such acurved cross-section may be circular, elliptical, oval or otherwisegenerally curved (i.e., comprised entirely of curved surfaces and/orvery short straight surfaces that effectively simulate a smoothly-curvedshape). If desired, the cross-section may include one or morerectilinear segments (e.g., a D-shape), or may be entirely rectilinear(e.g., a square or triangular shape). The cross-section of the channel202 also may taper to be larger at one end than the other, andpreferably reduces slightly in size as it approaches the distal end 206of the introducer. The retractor 100 may be shaped to match the shape ofthe introducer, and particularly the channel 202, as known in the art,however, it is not strictly required for the introducer 200 andretractor 100 to have matching geometric shapes.

The distal end 206 of the introducer is the end that is inserted intothe tissue. The distal end 206 transitions (preferably smoothly) fromthe cross-sectional shape of the channel 202 to a tip 208. The shape ofthe transitional region may be linear or curved, as viewed from adirection perpendicular to the longitudinal axis 204. A lineartransition would appear generally like an angular wedge, whereas acurved shape would appear as a wedge with bulging sides (e.g.,“bullet”-shaped). The transition also may be stepped or rectilinear(i.e. an abrupt termination at a flat tip 208), but these versions maybe less preferred.

The tip 208 may be closed to prevent the ingress of fluid or materialinto the channel 202, or it may be open by including a small opening. Ifused, an opening preferably has rounded or squared-off edges corners toprevent cutting of tissue as the introducer 200 is advanced through thetissue. In conventional introducers (e.g., those shown in Mangiardi I),an open tip can be desirable to allow a surgeon to remove tissue as theintroducer is advanced. However, the placement of the probe 210 in thechannel 202 may make this use impossible, and therefore a closed tip 208may be preferred. However, it still may be desirable to include anopening at the tip 208 to allow gas or fluid to be removed (orintroduced) in some applications.

The proximal end 212 of the channel 202 terminates at an opening 214that is configured to receive the probe 210, and also may be sized toallow visual inspection into the channel 202. Visual inspection may bedesirable to help the surgeon visualize the underlying tissue through atransparent distal end 206 of the introducer 200 or through transparentsidewalls of the channel 202. The introducer 200 may be provided withtransparent portions by forming the introducer from a transparentmaterial (e.g., polycarbonate), adding transparent windows to anotherwise opaque material, or providing uncovered openings through thematerial. Portions or all of the retractor 100 also may be transparent(e.g., transparent polycarbonate), to allow visualization through thecombined retractor assembly. Other embodiments may not have atransparent introducer 200, in which case the need to make the opening214 large enough to allow visualization is not necessary. The opening214 also may be sized to allow the introduction of one or more othersurgical instruments or apparatus, such as suction hoses, resectors,cauterizers, scopes, or the like.

The introducer 200 also may include an introducer connector 216 toconnect the introducer 200 to a retractor 100, as known in the art. Theintroducer 200 may be disposable or reusable. The introducer 200 may bemade of any material or materials suitable for surgical applications,such as sterilized polycarbonate, stainless steel, or the like. Theintroducer 200 also may be coated with chemicals, such as a lubricatingfilm, anti-coagulants or the like. Portions of the introducer 200 thatmay reflect lights during surgery may be coated with anti-reflectivepaints or coatings, or be surface treated (roughened or knurled) to helpreduce strong glare, as known in the art.

The probe 210 may be specially-designed to engage with and work with theintroducer 200, or it may be a pre-existing or otherwise availableprobe. The probe 210 preferably is a reusable device, but this is notstrictly required. Examples of probes that may be used with embodimentsof the invention are available from BrainLab AG of Feldkirchen, Germany,but other navigation probes may be used. The probe 210 may be used inconjunction with other navigation or surgical instruments, such as anavigation reference array, a probe manipulation arm, or other devices.

The probe 210 is secured to the introducer by a clamp mechanism 218. Theclamp mechanism 218 preferably is configured to securely hold the probe210 without damaging the probe 210. It is also preferable that the clampmechanism 218 can be operated easily by the surgeon. To this end, theclamp mechanism 218 may be a single-action clamp that is configured tobe operated by a single movement of the clamp actuating mechanism. Forexample, the clamp mechanism 218 may comprise a lever that requiresmovement from one position to another by a single movement of thesurgeon's hand, such as extending or retracting a thumb or finger, toengage the probe. However, two handed operation may be desirable orpossible in other embodiments, and an embodiment that facilitatessingle-motion operation is not necessarily intended to prohibitmanipulation by other movements.

Referring to FIGS. 2-5B, the exemplary clamp mechanism 218 is attachedat one side of the proximal end 212 of the introducer channel 202. Inthis case, the introducer 200 includes a clamp mounting flange 220 thatextends outward from the channel 202, and the clamp mechanism 218 issecured to the flange 220 by connectors such as pins, rivets, screws,bolts, welding (e.g., ultrasonic welding), adhesives, or other knownmeans. For example, the clamp mechanism 218 may be connected to theflange by two mounting screws (not shown) that pass through holes 222and into corresponding holes through the flange 220. Using thisarrangement, the clamp mechanism 218 may be mounted to introducers ofvarious shapes and sizes by adding a suitably-sized mounting flange toeach different introducer. In other embodiments, the clamp mechanism 218may be formed integrally with the introducer 200. In still otherembodiments, the flange 220 may be omitted and other mechanisms forattaching the clamp mechanism 218 to the introducer 200 may be used. Forexample, the clamp 218 may be connected to a conventional introducer, bya band clamp that wraps around the perimeter of the proximal end of theintroducer or by an expanding clamp that engages the inner surface ofthe introducer. Other alternatives will be readily apparent to personsof ordinary skill in the art in view of the present disclosure.

The exemplary clamp mechanism 218 includes a main body 224, a controlmember in the form of a clamp lever 226, and a clamp in the form of atension band 228 (FIG. 4) and anvil 230. The main body 224 protrudesradially inwards towards the centerline of the channel 202 andterminates at the anvil 230 at the inner end of the main body 224. Theanvil 230 may be shaped to receive the probe 210 in a notch. The notchmay be shaped to complement the shape of the probe 210 to help preciselyposition the probe 210. A notch that has tapered or converging walls maybe preferred because it helps center the probe 210 as the tension band228 is tightened around the probe 210. For example, the anvil 230 maycomprise a V-shaped notch (as shown) that extends parallel to thelongitudinal axis 204. Other notch shapes, such as a U-shaped notch or asquare notch, may be used in other embodiments. The anvil 230 also maycomprise a flat face, which can also help to effectively position theprobe 210 at a desired position if the tension band 228 is suitablyshaped.

Collectively, the tension band 228 and the anvil 230 form a clamp thatis axially aligned with the introducer channel 202. Thus, the clamp isable to hold the probe 210 within the introducer 200. The clamppreferably is located to position the probe 210 along the longitudinalcenterline 204, and preferably at the central geometric axis, of theintroducer 200.

The clamp lever 226 may be connected at the outer end of the main body224 by a pin 232 that fits within a slot 500 (FIG. 5A-B), or by otherpivoting or moving connectors such as integral pins, bosses, or slottedfeatures to connect to the main body 224. In the embodiment shown, thepin 232 allows the clamp lever 226 to rotate relative to the main body224 about a pin axis 234. The clamp lever 226 and the adjacent partspreferably are shaped so that the clamp lever 226 has a limitedrotational range of motion. For example, the clamp lever 226 may bemovable through a range of motion of about 90° between an unlockedposition shown in FIGS. 3 and 5A, and a locked position shown in FIGS. 2and 5B. The clamp lever 226 may have any shape, such as a curved shape,an angled shape, or a straight shape. A curved or angled shape may behelpful to assist the surgeon with gripping and moving the clamp lever226. In FIGS. 2-3, the clamp lever 226 is curved downward, but the clamplever 226 instead may be curved upward as shown in FIGS. 5A-B.Additional structures and operation of the clamp lever 226 are describedin more detail below.

The tension band 228 may comprise a strip of material (e.g., stainlesssteel, elastomeric compound, plastic, or the like) that is bent to forma loop 400 and two arms 402. Each arm 402 includes a respective hole404. The tension band 228 is movably associated with main body 224, suchas by positioning the arms 402 to slide within respective channels 502through the main body 224. The pin 232 passes through the two holes 404to connect the arms 402 to the clamp lever 226. When the parts areassembled, the loop 400 is located proximate to the anvil 230, andmovement of the clamp lever 226 causes the loop 400 to move towards andaway from the anvil 230. Thus, the loop 400 and the anvil 230 form thetwo operative parts of the clamp mechanism. It will be readilyappreciated that the tension band 228 also may comprise alternativestructures, such as a unitary molded plastic part or an assembly ofparts (e.g., a separate molded plastic loop 400 with connected metalarms 402). Other alternatives will be readily apparent to persons ofordinary skill in the art in view of the present disclosure. A singlearm 204 also may be used in other embodiments; for example, the tensionband 228 may comprise a “J-shaped” member having a loop 400 and a singlearm 402. The term “tension band” is intended to include any structurethat can be moved against the anvil to hold the probe 210 in place.

FIGS. 5A and 5B show the clamp lever 226 in the unlocked and lockedpositions, respectively. In these figures, the flange 220 is removed toshow the underside of the main body 224 and other parts. When the partsare installed, some or all of the lower surface 504 (or portionsthereof) or other parts of the main body 224 contact the flange 220 toconnect the clamp mechanism 218 to the introducer. Such connection maybe direct, or through an intermediate part, such as an adhesive layer, agasket, another functional part, and so on. The slot 500, in which thepin 232 is located, is formed by an arch-like portion of the main body224 that extends between two parts of the lower surface 504. When themain body 224 is connected to the flange 200, the pin 232 is captured inplace within the slot 500, but movable within the slot 500 towards andaway from the anvil 230. Similarly, the arms 402 of the tension band 228are captured within their respective channels 502. It will beappreciated that other embodiments may form the slot 500 or channels 502in other parts (e.g., in the flange 200), and the main body 224 maycomprise multiple assembled parts instead of an integral unit. It isalso envisioned that the arms 402 may extend partially or entirelyoutside the main body 224, instead of being captured in channels 502 asshown.

As noted above, the clamp lever 226 is shaped to rotate through about90° between the unlocked position in FIG. 5A, and the locked position inFIG. 5B. The clamp lever 226 includes an integrated cam mechanismcomprising a first face 506 and a second face 508. In the unlockedposition, the first face 506 of the clamp lever 226 faces the adjacentportion of the main body 224, and in the locked position, a second face508 of the clamp lever 226 faces the adjacent portion of the main body224. The first and second faces 506, 508 are positioned at differentdistances from the pin axis 234. More specifically, the first face 506is relatively close to the pin axis 234, and the second face 508 isrelatively far from the pin axis 234. Thus, the first and second faces506, 508 form a cam surface with respect to the pin axis 234. In thisarrangement, the pin 232 can move relatively close to the anvil 230 whenthe clamp lever 226 is in the unlocked position, which allows the loop400 of the tension band 228 to move further away from the anvil 230.When the clamp lever 226 is moved to the locked position, the secondface 508 moves between the pin 232 and the abutting surface of the mainbody 224, and forces the pin 232 to move further away from the anvil230. This causes the pin 232 to pull back on the tension band 228 tomove the loop 400 closer to the anvil 230. This movement locks the probe210 in place between the loop 400 and the anvil 230.

A transition surface 510 of the clamp lever 226 that connects the firstface 506 to the second face 508 may be rounded to ease movement betweenthe unlocked and locked positions. The transition surface 510 also mayinclude a portion that is even further from the pin axis 234 than thesecond face 508, which will prevent movement from the locked position tothe unlocked position without first applying an additional force to movepast the transition surface 510. For example, in the shown embodiment,the first and second surfaces 508, 510 are flat surfaces that fit flushto the main body 224, and the transition surface 510 comprises a roundedlobe. The use of the flat surfaces, and particularly forming the secondface 510 as a flat surface as shown, also provides a more positive feelto assure the surgeon that the clamp lever 226 is in the desiredposition.

While the foregoing latch arrangement is preferred for its ease of useand positive engagement and disengagement operation and feel, otherembodiments may use other mechanisms or means to hold the clamp lever226 in the locked position. For example, a spring-loaded latch may beused to hold the clamp lever 226 in the locked position, and uponreleasing the latch the tension in the tension band 228 may cause theclamp lever 226 to move back towards the unlocked position.

The slot 500 may be sloped to press the pin 232 downward—that is,towards the tip 208 of the introducer 200—as the pin 232 moves away fromthe anvil 230 to place the tension band 228 into the locked position. Toaccomplish this, the slot 500 could be sloped so that the far end of theslot 500 (i.e., the end most distant from the anvil 230) is closer tothe introducer tip 208 with respect to the longitudinal axis 204 thanthe near end of the slot 500. In this arrangement, a vertical force maybe generated through a slight downward movement of the tension band 228to urge the probe 210 towards the tip 208 of the introducer 200. Thismay be beneficial to help place the probe in the fully-seated positionduring latching.

The tension band 228 may comprise any material suitable for engaging andholding the probe 210 in place. For example the tension band 228 maycomprise spring steel, a loop of plastic or composite material, anelastic band, or other materials. In one embodiment, the tension band228 may comprise a strip of stainless steel that is 0.140 inches wide by0.020 inches thick having 0.0625 inch diameter holes and a loop 400 witha radius of 0.069 inches. The foregoing values are approximate, and areasonable range of dimensional values that still provide the essentialfunction of the tension band 228 could, of course, be used for thisparticular embodiment. Different values for these dimension could beused in other embodiments, and, as noted above, the tension band 228 maycomprise alternative constructions or shapes. Any suitable shape orconstruction may be used to provide a tension band 228 that act as aclamp to hold the probe 210 against the anvil. The design of alternativetension bands having alternative materials and/or dimensions will bewithin the skill of ordinary persons in the art, without undueexperimentation, in view of the present disclosure, and in view of thesizes and shapes of available probes 210.

The remaining parts of the clamp mechanism 218 may be made of anysuitable material or materials. In one example, the main body 224 andthe clamp lever 226 comprise molded polycarbonate, ABS plastic, cast ormachined metal, or the like.

Preferably, at least one part of the assembly will flex in order togenerate a restoring force to clamp the probe 210 firmly between thetension band 228 and the anvil 230. For example, the tension band 228(particularly the sections surrounding the holes 404) may stretchslightly to generate a restoring force. The tension band 228 may havecorrugations, slots, or other features to adjust its spring rate, andprovide a larger tolerance range for clamping the shaft of the probe210. Other parts that may flex include the pins 232, the anvil 230 (orother parts of the main body 224), the clamp lever 226, or the probe 210itself. Additional parts also may be added to provide a resilientrestoring force. For example, a strip of pliable rubber or otherflexible material may be provided on the loop 400 or anvil 230. Suchmaterial may also provide frictional grip to help prevent the probe 210from sliding in the longitudinal direction 204. For simplicity, theclamp mechanism 218 may be designed such that one part is particularlydesigned to provide the flexure necessary to generate a restoring force,and flexure of the remaining parts can be considered nominal. Forexample, the tension band 228 dimensions may be modified until thedesired clamping force (or range of forces) is obtained. As anotherexample, the main body 224 may include a resilient structure formed bycutouts 512, which allow the portion of the main body 224 against whichthe second face 508 of the clamp lever 226 abuts to flex relative to therest of the main body 224 to provide a resilient force to hold thetension band 228 in tension.

The clamping force is required only to prevent unwanted movement of theprobe 210 during normal surgery conditions, and it is expected that thetypical forces that would be applied during surgery that could separatethe probe 210 from the introducer 200 will be less than four (4) pounds.Persons of ordinary skill in the art of mechanical design will be ableto construct the clamp mechanism 218 to hold the probe 210 with anydesired amount of holding force without undue experimentation.

The clamp may be configured to be operated during a surgical procedure,and preferably can be operated with one hand. For example, the surgeonusing this embodiment can hold the introducer 200 by looping the middlefinger below the introducer connector 216, looping the index fingerbelow the flange 220, and pushing or pulling on the clamp lever 226 withthe thumb. With the other hand, the surgeon can hold the probe 210 orother objects. This allows the surgeon to hold the introducer 200 inplace while locking or unlocking the clamp mechanism 218 to remove,adjust, or install the probe 210 during a surgical procedure. The rangeof movement of the clamp lever 226 may be adjusted as desired, but it ispreferably for the clamp lever 226 to rotate through a range of about90° or less, in order to simplify and ease operation between the clampedand unclamped positions.

The clamp mechanism 218 also may be configured to minimize obstructingthe surgeon's visual or physical access through opening 214. Forexample, the side walls of the main body 224 may converge as theyapproach the anvil 230, and the anvil 230 and loop 400 may be made onlylarge enough as needed to hold the probe 210. This minimizes the size ofthe clamp mechanism 218, as viewed along the longitudinal direction, andhelps the surgeon look down into or pass instruments into the channel202.

Referring now to FIG. 6, the introducer 200 and clamp mechanism 218assembly preferably includes a stop surface 600 that the probe's tip 602contacts (directly or through an intermediate part) when the probe 210is fully seated in the introducer 200 to place the probe 210 in theproper registration position. The registration position is the positionat which the probe 210 is expected to be for purposes of using the probe210 to accurately determine the position of the introducer 200. Forexample, the probe's tip 602 may be located at a known position inrelation to the navigation system, and, if the probe tip 602 is locatedclose to the distal tip 208 of the introducer 200, then the probe tip'sposition may be used as a nominal value for the location of theintroducer tip 208. Alternatively, the system can be programmed, asknown in the art, to account for the offset in locations between theprobe tip 602 and the introducer tip 208, in which case the system canmore accurately track the introducer tip's location (provided the probetip 602 remains properly registered with the introducer 200).

Regardless of how the navigation system is programmed, it relies on aknown spatial correlation between the probe tip 602 and the introducer'stip 208 (or whichever part of the introducer 200 is desired to betracked). If the probe tip 602 is not advanced far enough into theintroducer 200, then the introducer tip 208 will be offset deeper intothe tissue than what the navigation system indicates. As such, a stopsurface 600 is provided to position the probe tip 602 at the properregistration position.

The stop surface 600 preferably is part of the introducer itself, but itmay be formed as a receptacle mounted on the clamp mechanism 218 or asanother attached part.

In the shown exemplary embodiment, the stop surface 600 comprises aninterior surface at the distal tip 208 of the introducer 200. FIG. 6shows the probe tip 602 spaced slightly from the stop surface 600, butadvancing the probe 210 further down will bring the probe tip 602 intocontact with the stop surface 600. In this case, contact is via anintermediate cup-like part of a registration indicator 604 (discussedbelow), but in embodiments that do not have a registration indicator 604contact may be directly between the probe tip 602 and the stop surface600. In this embodiment, the offset between the probe tip 602 and theintroducer tip 208 can be very small (e.g., <1 mm). In some cases, thissmall amount of offset may be ignored, but it may nonetheless beincluded in the computations of the introducer tip location. The stopsurface 600 also may be tapered or otherwise shaped to guide the probetip 602 in to the proper location (e.g., along the central geometricaxis of the introducer 200).

It will be appreciated that the stop surface 600 may be configured tocontact the probe 210 at a location other than the probe tip 602. Forexample, the stop surface 600 may comprise a circular ring orarrangement of ribs that surround the probe tip 602 but hold the probe210 along the tapered surface of the probe 210 immediately above theprobe tip 602. In such embodiments, care should be taken to make thesupport surface 600 strong enough that it will not deform as the probe210 is pressed downward.

Embodiments also may include a registration indicator to indicatewhether the probe 210 is fully inserted into the registration position.While not strictly necessary in all embodiments, a registrationindicator can be helpful to ensure that the probe 210 is properlyinstalled into the introducer 200, and that the probe 210 has notslipped during use. It is expected that a registration indicator can behelpful for all systems that combine a probe 210 with an introducer 200,but it may be particularly beneficial in embodiments in whichintraoperative removal and reinstallation of the probe 210 is possibleor expected.

An example of a registration indicator 604 is shown in FIGS. 2, 6, 7Aand 7B. The registration indicator 604 comprises an elongate member 606that extends from a proximal indicator end 608 located at or near theproximal end 212 of the channel 202, to a distal indicator end 610located inside the channel 202. The elongate member 606 may comprise atube, such as shown, to help guide the probe 210 along the length of theelongate member 606, and to prevent the surgeon from inadvertentlydirecting the probe 210 at an improper angle relative to the introducer.The distal indicator end 610 may comprise a closed tip that is taperedtowards the center so that the probe 210 will center itself when it ispressed downward into the registration indicator 604 (e.g., to centerthe probe 210 along the central geometric axis of the introducer 200).If desired, the elongate member 606 may include one or more inspectionports 622 to allow visual inspection inside the elongate member 606 tomake sure nothing is blocking free access to the distal indicator end610. In other embodiments, the elongate member 606 may comprise an openchannel that partially wraps around the probe 210, or a simple rod thatdoes not wrap around the probe 210. Also, the closed tip of the distalindicator end 610 may be replaced by a partial or complete ring-likeshape that wraps around the probe 210 at a location above the probe tip602. Other alternatives will be readily apparent to persons of ordinaryskill in the art in view of the present disclosure. The registrationindicator 604 may be provided as a molded plastic part, as a formedmetal part, or by other manufacturing processes.

The elongate member 606 is slideably mounted to the introducer 200, suchas by positioning the proximal indicator end 608 inside an upper slidingmount 612 and the distal indicator end 610 inside a lower sliding mount614. The upper sliding mount 612 in this example comprises a ring joinedto the main body 224 of the clamp mechanism 218, either by integralforming or separate manufacture and attachment. The upper sliding mount612 closely surrounds a similarly-shaped portion of the proximalindicator end 608 to provide sliding movement therebetween along thelongitudinal axis 204, while generally preventing relative movement indirections perpendicular to the longitudinal axis 204. Similarly, thelower sliding mount 614 comprises a ring or tube, formed at the distalend 206 of the introducer 200, that surrounds the distal indicator end610 to provide sliding movement therebetween along the longitudinal axis204, while generally preventing relative movement in directionsperpendicular to the longitudinal axis 204. It will be appreciated thatother arrangements of sliding parts or shapes may be used in otherembodiments. For example, the ring that forms the upper sliding mount612 or the lower sliding mount 614 may be replaced by a pattern of ribsor pins that prevent lateral movement away from the longitudinal axis204. By way of example, FIG. 2 shows the lower sliding mount 614 formedwith ribs 236. Other alternatives will be readily apparent to persons ofordinary skill in the art in view of the present disclosure.

A resilient member, such as a spring 616, may be provided to bias theregistration indicator 604 away from the tip 208 of the introducer 200.In this example, the spring 616 comprises a coil spring that wrapsaround the elongate member 606 and extends between a stop ring 618 onthe outer surface of the elongate member 606 and an upper surface of thelower sliding mount 614. The stop ring 618 may be provided integrallywith the elongate member 606, or added as a separate part. The spring616 may comprise any suitable material, such as spring steel orresilient plastic. Also, other kinds of springs and spring locations maybe used in other embodiments. For example, the coil spring may bereplaced by a leaf spring, a cantilevered beam, or an elastomericmaterial. As another example, the spring may be located between thedistal indicator end 610 and the stop surface 600.

The registration indicator 604 may be captured in place by a lip 620,formed on the elongate member 606, that abuts the bottom of the clamp'smain body 224, or by other interacting structures. In this example, theregistration indicator 604 may be installed by sliding the spring 616over the distal indicator end 610, placing this subassembly into theintroducer 200, then attaching the clamp mechanism 218 to hold theregistration indicator 604. With this construction, the entire assemblyof the introducer 200, clamp mechanism 218, and registration indicator604 has no loose parts, which helps provide a high degree of safety inthe surgery environment.

In use, the elongate member 606 is movable between a first position inwhich the proximal indicator end 608 is positioned to indicate that theprobe 210 is not in registration with the introducer 200, and a secondposition in which the proximal indicator end 608 is positioned toindicate that the probe 210 is in registration with the introducer 200.In the registered position, the probe tip 602 may be closely adjacent tothe introducer tip 208 (e.g., within about 2.0 mm, 1.0 mm, or less), orthe probe tip 602 may be at a larger, but known, position relative tothe introducer tip 208. The spring 616 biases the registration indicatortowards the first position. When it is desired to install a probe 210,the surgeon inserts the probe tip 602 into the ring-like upper slidingmount 612 and advances the probe tip 602 until it contacts the distalindicator end 610. The surgeon continues advancing the probe tip 602 tocompress the spring 616 and slide the registration indicator from thefirst position to the second position. When the registration indicator604 indicates that the probe 210 is in proper registration with theintroducer 200, the surgeon can engage the clamp mechanism 218 to holdthe probe 210 in place.

The registration indicator 604 can be configured in any suitable way toindicate improper and proper registration to the surgeon. For example,FIGS. 7A and 7B show the registration indicator 604 in the unregisteredand registered positions, respectively. In the unregistered position, anupper indicator surface 700 of the proximal indicator end 608 ispositioned above the upper sliding mount 612 to indicate that the probe210 is not in proper registration. When the probe 210 is fully inserted,the proximal indicator end 608 is moved down to the second position, inwhich the indicator surface 700 is not visible behind the upper slidingmount 612, to indicate that the probe 210 is now in proper registrationwith the introducer 200. At this point, the clamp mechanism 218 may beengaged to hold the parts in proper registration. If the probe 210 slipswithin the clamp mechanism 218 before or during surgery, the spring 616will move the registration indicator 604 upwards away from theintroducer tip 208 to immediately indicate to the surgeon that the probe210 is no longer in registration.

The indicator surface 700 may be brightly colored (e.g., orange, yellowor red) to help show when it is in the unregistered position. Theindicator surface 700 also may include markings such as a textualindication that registration has not been achieved, a scale or ruler toindicate how far the parts are from registration, or other markings.Other alternatives will be readily apparent. For example, the indicatorsurface 700 may comprise a pointer that remains visible at all times,but points to a word (e.g., “bad”) or other indicia (e.g., a red stripe)when the parts are not in registration, and points to another word(e.g., “good”) or other indicia (e.g., a green stripe) when the partsare in registration. Other variations will be readily apparent in viewof the present disclosure.

The registration indicator 604 also may be protected from inadvertentmovement, to prevent it from accidentally being pressed down against thebias of the spring 616 when the probe 210 is not fully seated in theregistration position. For example, the registration indicator 604 couldbe surrounded by a transparent cover or a structure that extends fromthe upper sliding mount 612. Such structure preferably will not blockthe surgeon's view of the registration indicator 604.

The shown registration indicator 604 is not operatively connected to theclamp mechanism 218, so that the registration indicator 604 will operateregardless of the clamp's position. In other embodiments, theregistration indicator 604 may be interconnected to the clamp mechanism218, but in such cases the registration indicator 604 may be usefulsimply to indicate when the clamp mechanism 218 has been disengaged orslipped.

Another exemplary embodiment is illustrated in FIGS. 8, 9A and 9B. Here,the retractor system includes a retractor 800 and an introducer 802 thatselectively installs inside the retractor 800. The retractor 800 andintroducer 802 have an oval, round, or other cross-sectional shape, andthe cross-sectional size of each may gradually decrease towards thedistal ends thereof. The retractor 800 and introducer 802 also may bepartially or wholly transparent to allow visualization of tissuetherethrough. The retractor 804 may include a handle 804, and a lock 806may be provided on the introducer 802 or retractor 800 to selectivelylock the introducer 802 and retractor 800 together. In this case, thelock 806 engages the handle 804, but other arrangements may be used. Thehandle 804 also may include a ridge 808 or other structure to engage aconventional surgical clamp (not shown).

The introducer 802 includes a clamp mechanism 812 that is configured toselectively hold a navigation probe 810. The clamp mechanism 812includes a clamp mount 814 that extends from (and may be integrallyformed with) the proximal end of the introducer 802, a clamp body 816and associated anvil 818 that is secured to the clamp mount 814 byscrews 820 or the like, a tension band 822, a pivot pin 824 and a clamplever 826. The clamp mechanism 812 is similar to those describedpreviously herein, but the clamp lever 826 includes one or moreprotrusions 828 that hold the clamp lever 826 in the locked position,and cooperates with the clamp body 816 to generate a force to hold thetension band 822 against the anvil 818.

The operation of the clamp lever 826 is shown in FIGS. 9A and 9B, whichshow the clamp mechanism 812 in the unlocked and locked positions,respectively. The clamp lever 826 is pivotally mounted on the pivot pin824, such as described previously herein, with the protrusion 828 facingan abutment surface 830 on the clamp body 816. As shown in FIG. 9A, theclamp lever 826 starts in a first angular position relative to the restof the clamp mechanism 812. In this position, the protrusion 828 ispositioned to allow the pivot pin 824 to be positioned a first distanced₁ from the abutment surface 830. When the clamp lever 826 is rotatedabout the pivot pin 824 to the locked position, as shown in FIG. 9B, theprotrusion 828 presses against the abutment surface 830 to force thepivot pin 824 to a second distance d₂ from the clamp body 816. Thesecond distance d₂ is greater than the first distance d₁, and thus thepivot pin 824 pulls the tension band 820 towards the anvil 818 to clampthe probe 810 in place.

It will be appreciated from the foregoing explanation that theprotrusion 828 acts as a rotating cam to selectively clamp or unclampthe probe 810. In the unclamped position, the pivot pin 824 may notnecessarily move back to the first distance d₁, but it is free to do soupon application of a nominal force, which allows installation of theprobe 810 between the tension band 820 and the anvil 818. Alternatively,a return spring (not shown) or other resilient device may be used tomove the pivot pin 824 to the first position d₁, which may be helpful toallow easier installation of the probe 810.

As noted above, the protrusion 828 is configured to hold the clamp lever826 in the locked position. This is achieved by configuring theprotrusion 828 as a so-called “over-center” mechanism that requires anapplication of force to move the clamp lever 826 out of the lockedposition. In the illustrated example, the protrusion 828 is shaped witha point of maximum distance 900 that is located at a greatest distancefrom the pivot pin 824. The distance between the pivot pin 824 and theabutment surface 830 is greatest when the point of maximum distance 900is directly between the pivot pin 824 and the abutment surface 830, andthe force generated to push the pivot pin 824 away from the abutmentsurface 830 is also greatest at this point. The point of maximumdistance 900 contacts the abutment surface 830 slightly before the clamplever 826 reaches the locked position. Thus, when the clamp lever 826 isin the locked position such as shown in FIG. 9B, the second distance d₂is slightly less than the maximum distance that is achieved when thepoint of maximum distance 900 contacts the abutment surface 830. Toremove the clamp lever 826 from the locked position, the user must applya force to rotate the point of maximum distance 900 past the abutmentsurface. The magnitude of this force can be modified by altering theshape of the protrusion surface 828 and abutment surface 830, byaltering the coefficient of friction between the parts, and by othermethods as will be appreciated from the foregoing description. Otherembodiments also may use other over-center mechanisms, as known in theart.

The amount of force required to rotate the clamp lever 826 and themagnitude of the clamping force generated to hold the probe 810 in placeare a function of the geometric relationships of the parts (e.g., thesizes and shapes of the protrusion 828 and abutment surface 830), andalso the resilience of the parts (e.g., the flexibility of the tensionband 820). In the shown example, the rotation and retaining force areregulated by resiliently mounting the abutment surface 830 to theremainder of the clamp body 816. For example, a slot 832 may be providedbehind the abutment surface 820 to mount the abutment surface 830 in acantilevered configuration that allows the abutment surface to flextowards the rest of the clamp body 816. As the protrusion 828 is movedagainst the abutment surface 830 by rotating the clamp lever 826, theabutment surface 830 can move towards the clamp body 816. When theprotrusion 828 is in the final locked position as shown in FIG. 9B, theabutment surface 830 preferably is still flexed towards the clamp body816 to some degree to provide a resilient restoring force that holds theprobe 810 in place.

Other mechanisms for providing a resilient force to hold the probe 810may be used in other embodiments. For example, the tension band 820 maybe elastically extended when the pivot pin 824 is moved to the seconddistance d₂. As another example, the anvil 818 may be resilientlymounted. As another example, the clamp lever 826 may have a slot behindthe protrusion 828 to allow the protrusion 828 to flex somewhat. Otheralternatives will be readily apparent to persons of ordinary skill inthe art in view of the present disclosure.

The introducer 802 also may include a registration indicator 834. Inthis example, the registration indicator comprises a shaft 836 with anindicator surface 838 at the proximal end, and a probe tip receptacle840 at the distal end. The shaft 836 may comprise a solid-walled tube,which minimizes the possibility that the tip of the probe 810 will beturned to the side and miss the tip receptacle 840. Alternatively theshaft 836 may comprise a rod or a tube with side openings to facilitateviewing of the probe 810 and removal of body fluids and the like thatmight enter during surgery. The tip receptacle 840 may be formed as partof the shaft 836, or formed separately from and joined to the shaft 836by any suitable bonding method (e.g., ultrasonic welding, laser welding,adhesives, press-fitment, etc.). For example the shown tip receptacle840 is a machined metal or molded plastic part that is joined to theshaft 836. The tip receptacle 840 also may include an opening 842through which the proper seating of the probe tip can be confirmed andfluids can be evacuated.

The registration indicator 834 may be mounted to the introducer 802 bybeing captured in place between the clamp body 816 and the distal end ofthe introducer 802. For example, the proximal end of the registrationindicator 834 may be slideably mounted in a retaining ring 844 on theclamp body 816, and the distal end of the registration indicator 834 maybe slideably mounted in a retaining cup 902 at the distal end of theintroducer 802. The retaining cup 902 may be configured to allow the tipreceptacle 840 and probe tip to get close to the distal exterior end ofthe introducer 802, to minimize or eliminate the need to account for thedistance between the probe tip and the distal exterior end of theintroducer 802 during computer-aided navigation. However, this is notstrictly required, and some degree of offset can be readily accountedfor in calculating the position of the introducer 802 during surgery.The proximal end of the registration indicator 834 includes a lip 846that abuts the bottom of the clamp body 816 to prevent the registrationindicator 834 from being removed.

A spring 848 is positioned between the retaining cup 902 and the shaft836 to bias the registration indicator 834 away from the distal end ofthe introducer 802. In this case, the spring 836 extends all the wayfrom the distal end of the introducer 802 (e.g., the top lip of theretaining cup 902), to the proximal end of the registration indicator834 where the shaft 826 expands radially to transition to the indicatorsurface 838. Other alternatives to this spring arrangement will bereadily apparent to persons of ordinary skill in the art in view of thepresent disclosure.

As shown in FIG. 9A, the indicator surface 838 is visible above theretaining ring 844 when the probe 810 is not pressed down against thebias of the spring 848. The probe 810 is fully installed by pressingdownward to compress the spring 848, so that the tip of the probe 810 isfully-seated in the tip receptacle 840, and the tip receptacle 840 isfully-seated in the introducer 802, as shown in FIG. 9B. In the fullyinstalled position, the indicator surface 838 is no longer visible abovethe retaining ring 844, which clearly indicates that the parts in properposition for use.

The foregoing embodiments are expected to provide several benefits tothe surgeon during surgery. For example, the introducer and probe can besecured together easily without requiring excessive manipulation orforce applied to either part (which is particularly useful whereintraoperative removal, reattachment, or adjustment are desired), andthe cam lock design is easy to use and gives reliable feedback toindicate that the clamp is properly engaged. Moreover, the clamp can beoperated with a single movement of the clamp control mechanism by simplyflipping the clamp lever from one position to the other. Also, the partsare securely connected to provide accurate guidance. Still further, theregistration indicator provides immediate feedback if the probe releasesor shifts out of the registration position relative to the introducer.

The foregoing embodiments also may provide additional manufacturing andoperation benefits. For example, the various parts have been combined orintegrated to reduce part count to eliminate the possibility of losingloose parts. Also, the parts may be easily molded without requiringexcessive tolerance control or major post-molding machining, and theassembled introducer also is manufacturable with relative ease and lowcost. Still further, the clamp and registration indicator, or portionsthereof, may be manufactured as separate parts that can be integratedinto a variety of differently-sized or differently-shaped introducers.Thus, an entire product line of different introducers may be equippedwith a single type of clamp or registration indicator with relativeease.

It will be appreciated that the clamp mechanisms described in theforegoing exemplary embodiments may be modified in a variety of ways toprovide a surgical introducer that connects to a navigation probe. Forexample, the pin and tension band may be fixed to the clamp body, and acam surface on the lever may slide the anvil towards and away from thetension band. In another embodiment, the cam surface may be madeseparately and mounted to the clamp lever or operated remotely by thecam lever through a linkage. As yet another example, the clampingmechanism may be replaced by a “clothespin” style clamp having a fixedjaw and a pivotally-connected movable jaw. The clamp also may comprisetwo hooks that move in opposite directions relative to one another(either by both moving or one being fixed and the other moving) to pullon opposite sides of the probe to hold it in place. As another example,the clamp lever may rotate about an axis that is parallel to or at otherangles to the longitudinal axis 204. In still other embodiments, theclamp lever 226 may be provided with a double-acting spring, such asused commonly in electrical switches and the like, that urges the clamptowards the open and closed positions. The clamp also may comprise aslot that holds the probe, and a mechanism to selectively squeeze theslot to compress the probe in place. The cam mechanism also may bemodified, such as by replacing the simple facing cam surfaces with aspiral-shape slot formed in a rotating disc that drives a pin to clampthe probe in place. The clamp also may comprise a ratchet mechanism topull the clamp shut on the probe through repeated movements of theratchet. Other clamps may use a moving wedge or an eccentric pin todrive the clamp closed on the probe. Other alternatives will be readilyapparent to persons of ordinary skill in the art in view of the presentdisclosure, and additional exemplary constructions are described in thepriority documents for the present application, which are incorporatedherein by reference.

FIG. 10 shows another clamp 1000. In this embodiment, the clamp 1000uses a collet that includes a tapered tube 1002 that has a slot 1004 atone end, and a passage through which the probe 1006 fits. The tube 1002may be connected to the inner wall of the introducer 1008 by a post1010. The probe 1006 is locked in place by compressing the tube 1002 atthe location of the slot 1004. In this example, a collar 1012 isprovided to slide up the tube 1002. As the collar 1012 moves upwards,the fixed inner diameter of the collar 1012 encounters the tapered outerbody of the tube 1002, and generates a force to compress the tube 1002against the probe 1006 at the location of the slot 1004. The collar 1012may be operated by any suitable mechanism, such as a cam lever 1014 thatis connected to the collar 1012 by a linkage 1016. The linkage 1016 maycomprise any suitable force-transferring mechanism, as known in the art,and preferably provides the collar 1012 with a relatively linearmovement. A latch 1018 may be provided to engage an opening 1020 throughthe cam lever 1014 (or any other part of the cam lever 1014 or linkage1016), to hold the cam lever 1014 in the locked position until releasedby the surgeon.

Other alternatives to the disclosed clamps will be readily apparent topersons of ordinary skill in the art in view of the present disclosure.As one non-limiting example, a threaded fastener may be used to securethe probe to the introducer in the fashion of a conventional “lockingscrew.” However, adding a threaded fastener disadvantageously increasesthe number of articles present at the surgery site, and requires specialattention to prevent the threaded fastener from coming free from theintroducer and possibly entering the patient's body, or modification toprevent the fastener from coming free at all. Threaded fasteners alsomay be vulnerable to contamination that can make operation moredifficult, require relatively precise machining, can lack a positiveengagement feel, can damage the probe, and do not clearly indicatewhether they are engaged or not. Moreover, threaded fasteners can bedifficult to turn with gloved fingers and can require two hands tosecure. Still further, threaded fasteners are not single-actionmechanisms, and they cannot be operated with a single movement—instead,the surgeon must repeatedly rotate the screw head to rotate the fastenerinto position. Such movements tend to move the parts around, and maymake it difficult to use the threaded fastener during surgery whenmaintaining precise positioning of the introducer may be critical.Despite this, a system that uses a threaded fastener may still be used,particularly where setup can be performed remotely from the patient, andsuch systems are also expected to benefit by the addition of aregistration indicator to illustrate when the probe is out of properregistration with the introducer.

The present disclosure also contemplates a variety of modifications tothe registration indicator. For example, the spring may abut a structurethat extends from the bottom of the main body of the mount, instead ofabutting against a part of the introducer. As another example, theregistration indicator may comprise a moving part that is captured in areceptacle within the introducer, and is not part of the clamp mountingmechanism. The registration indicator also may comprise any suitableapparatus to indicate the position of the probe, such as a simpleprotruding pin or a rotating gauge to show the position of the probemore precisely. The registration indicator also may comprise alternativestructures, such as a band of material that extends into the introducerand is flexed by the probe to operate a pivoting flag or other indicatorwhen the probe is installed in the introducer. Also, the arrangement ofthe illustrated upper and lower sliding mounts may be reconfigured toprovide other means for holding the registration indicator to slide onlyalong the longitudinal axis. For example, the upper and lower slidingmounts may be replaced by a one or two mounts provided on the clampbody. This latter embodiment is expected to be useful if the introducerhas an opening at the tip and it is desired to be able to access thatopening while the probe and registration indicator are mounted in place,because the probe tip can be offset from the introducer tip by somedistance. Other alternatives will be readily apparent to persons ofordinary skill in the art in view of the present disclosure.

It will be appreciated that the embodiments described herein can berecombined in any suitable manner. For example, the clamps andregistration indicators may be connected directly to an introducer, orconnected indirectly to an introducer by way of intermediate parts or anadapter that fits inside an introducer. The clamps and registrationindicators also may be used directly with retractors. For example, aftera retractor as described in a reference such as Mangiardi I is placed atthe surgery site, an adapter with a clamp or registration indicator tohold a navigation probe may be placed in or connected to the retractorto confirm that the retractor is in the correct position or to allowfurther movement of the retractor.

It will also be appreciated that the clamps and registration indicatorsalso may be combined with various different locking mechanisms, positionindicators, or other features. Also, parts described in the variousembodiments may be recombined with parts from other embodiments in anysuitable manner. Still further, it will be understood that the clamp andregistration indicator are two separate inventions that may be usedindependently and without the other. For example, a clamp may beprovided without a registration indicator if one is not desired (e.g.,to provide greater visibility through the introducer), and aregistration indicator may be used without a clamp (e.g., where thesurgeon wishes to manually hold the probe in place during use). Otheralternatives will be readily apparent to persons of ordinary skill inthe art in view of the present disclosure.

Terms of direction or frames of reference are also not intended to belimiting. For example, the term “vertical” and directions that relate tothe vertical direction's frame of reference (i.e., “horizontal,”“lateral,” etc.) have been used herein for expedience to describeembodiments as they would be used with the longitudinal axis 204 of theintroducer pointed in the global vertical direction (i.e., along thedirection of gravitational pull). It will be appreciated that theintroducer can be reoriented to direct the longitudinal axis 204 indirections other than the global vertical direction, and simple rotationof the frame of reference in this manner would not cause commercialembodiments to deviate from the teachings herein.

The present disclosure describes a number of new, useful and nonobviousfeatures and/or combinations of features that may be used alone ortogether. The embodiments described herein are all exemplary, and arenot intended to limit the scope of the inventions. It will beappreciated that the inventions described herein can be modified andadapted in various and equivalent ways, and all such modifications andadaptations are intended to be included in the scope of this disclosureand the appended claims.

We claim:
 1. A delicate tissue retraction system for use with anavigation probe having a probe shaft and a probe tip at a distal end ofthe probe shaft, the delicate tissue retraction system comprising: aretractor comprising a hollow tubular retractor passage extending alonga longitudinal axis from a proximal retractor end to a distal retractorend; an introducer comprising an introducer wall forming an introducerchannel extending from a proximal introducer end to a distal introducerend, the introducer being configured to be removably installed withinthe retractor such that the proximal introducer end and distalintroducer end are located along the longitudinal axis and the distalintroducer end extends beyond the distal retractor end; and a clampmechanism located at the proximal introducer end, the clamp mechanismcomprising: a probe shaft receptacle suspended from the introducer wallat a location within the introducer channel with one or more open spacesbetween the introducer wall and the probe shaft receptacle, the probeshaft receptacle having a clamp passage formed by an interior wall ofthe probe shaft receptacle, the clamp passage being axially aligned withthe introducer channel and dimensioned to receive the probe shafttherethrough, and a clamp configured to selectively reduce a size of atleast a first portion of the clamp passage to selectively hold the probeshaft at a fixed position relative to the introducer.
 2. The delicatetissue retraction system of claim 1, wherein the probe shaft receptaclecomprises a slot extending along the longitudinal axis and intersectingthe clamp passage at the first portion of the clamp passage.
 3. Thedelicate tissue retraction system of claim 2, wherein the clamp isconfigured to compress the probe shaft receptacle at the slot to therebyhold the probe shaft at the fixed position relative to the introducer.4. The delicate tissue retraction system of claim 3, wherein an outersurface of the probe shaft receptacle at the slot comprises a taperedwall, and the clamp comprises a collar that surrounds the tapered walland is movable between a first position in which the probe shaft ismovable relative to the probe shaft receptacle and a second position inwhich the probe shaft is held at the fixed position relative to theprobe shaft receptacle.
 5. The delicate tissue retraction system ofclaim 1, wherein the clamp is configured to press on an outer surface ofthe probe shaft receptacle to selectively reduce the size of the firstportion of the clamp passage to selectively hold the probe shaft at thefixed position relative to the introducer.
 6. The delicate tissueretraction system of claim 1, wherein the clamp mechanism spans theintroducer channel from a first point at the introducer wall to a secondpoint at the introducer wall.
 7. The delicate tissue retraction systemof claim 1, wherein at least a portion of the introducer wall comprisesa transparent material, and the one or more open spaces are dimensionedto allow visualization past the probe shaft receptacle, along theintroducer channel, and through the transparent material.
 8. Thedelicate tissue retraction system of claim 1, wherein the introducercomprises a mount extending into the introducer channel at the distalintroducer end and positioned to surround the probe tip when thenavigation probe is at a fully inserted position within the introducer.9. The delicate tissue retraction system of claim 8, wherein the mountcomprises a ring.
 10. The delicate tissue retraction system of claim 8,wherein the mount comprises a plurality of ribs.
 11. The delicate tissueretraction system of claim 1, wherein the first portion of the clamppassage comprises a fixed anvil and a movable clamp part, and the clampfurther comprises a control member that is rotatable between an openposition in which the movable clamp part is relatively far from thefixed anvil, and a closed position in which the movable clamp part isrelatively close to the fixed anvil to hold the probe shaft at the fixedposition relative to the introducer.
 12. The delicate tissue retractionsystem of claim 11, wherein the movable clamp part comprises a tensionband.
 13. The delicate tissue retraction system of claim 11, wherein thecontrol member comprises a cam that is rotatable between an unlockedposition in which the movable clamp part is in the open position, and alocked position in which the movable clamp part is in the closedposition.
 14. The delicate tissue retraction system of claim 11, whereinthe control member comprises a lever that is pivotally mounted to theremainder of the clamp mechanism to rotate through an angle of about 90°between the open position and the closed position.
 15. The delicatetissue retraction system of claim 1, wherein the clamp passage islocated at a central geometric axis of the introducer.
 16. The delicatetissue retraction system of claim 15, wherein the distal introducer endterminates at an introducer tip located along the central geometric axisof the introducer.
 17. The delicate tissue retraction system of claim 1,further comprising a registration indicator configured to indicate whenthe navigation probe is at a proper registration position with respectto the introducer.
 18. The delicate tissue retraction system of claim17, wherein the registration indicator is movably mounted to the clampmechanism to slide along the longitudinal axis between a first indicatorposition in which the registration indicator indicates that the probe isnot at the proper registration position, and a second indicator positionin which the registration indicator indicates that the probe is at theproper registration position.
 19. The delicate tissue retraction systemof claim 18, wherein the registration indicator comprises a proximalindicator end, a distal indicator end, and a shaft joining the proximalindicator end and the distal indicator end.
 20. The delicate tissueretraction system of claim 19, wherein the shaft comprises a hollowtube.
 21. The delicate tissue retraction system of claim 19, wherein thedistal indicator end comprises a probe tip receptacle having an openingthrough which the position of the probe tip can be viewed.
 22. Thedelicate tissue retraction system of claim 18, wherein the registrationindicator comprises a resilient member configured to bias theregistration member to move towards the first indicator position. 23.The delicate tissue retraction system of claim 1, wherein the clampmechanism is removably connected to the introducer.
 24. The delicatetissue retraction system of claim 23, wherein the clamp mechanism issecured to the introducer by screws.